Process for the preparation of N,o-substituted mono- and/or polyurethanes

ABSTRACT

The invention describes a process for the preparation of N,o-substituted mono- and/or polyurethanes of formula 
     
         R.sup.1 [--NHCOOR.sup.2 ].sub.n, 
    
     in which 
     R 1  is an aliphatic, cycloaliphatic, aromatic, araliphatic, or heterocyclic radical, which may be substituted, 
     R 2  is an aliphatic, cycloaliphatic, or araliphatic radical which may be substituted with alkoxy or polyoxyalkylene groups, and 
     n is a whole number from 1 to 5, 
     through the reaction of N-substituted allophanates and/or polyallophanates with alcohols R 2  OH in the presence or absence of catalysts at temperatures of at least 160° C., preferably from 165° to 250° C.

This is a division, of application Ser. No. 632,840 filed July 20, 1984now U.S. Pat. No. 4,695,645.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a process for the preparation ofN,o-substituted mono- and/or polyurethanes of formula

    R.sup.1 [-NHCOOR.sup.2 ].sub.n,

in which

R¹ is an aliphatic, cycloaliphatic, aromatic, araliphatic, orheterocyclic radical, which may be substituted,

R² is an aliphatic, cycloaliphatic, or araliphatic radical which may besubstituted with alkoxy or polyoxyalkylene groups, and

n is a whole number from 1 to 5.

More particularly, the invention relates to a process for thepreparation of N,o-substituted mono- and/or polyurethanes through thereaction of N-substituted allophanates and/or polyallophanates withalcohols R² OH in the presence or absence of catalysts at temperaturesof at least 160° C., preferably from 165° to 250° C.

2. Prior Art

Industrially, urethanes are generally produced by the reaction ofisocyanates with alcohols or of chloroformates with amines, whereby boththe isocyanates and the chloroformates are obtained through thephosgenation of the corresponding amines and cleaving off hydrogenchloride or by the phosgenation of the alcohols (Methoden de organischenChemie, Houben-Weyl, vol. 8, pp. 137, 120, and 101, Stuttgart: GeorgThieme Verlag, 1952). These processes are very expensive from acommercial standpoint; in addition, the use of phosgene results insignificant disadvantages relating to the necessary safety andenvironmental measures.

Recently, a series of processes for producing urethanes has beendescribed in which carboxylic acid derivatives are reacted with primaryamines in the presence of alcohols.

In European Patent Application No. 18 581 (Canadian Pat. No. 1,121,373),aryl-mono- and/or -polyurethanes are prepared by reactingo-alkylcarbamates with primary aromatic mono- and/or polyamines in thepresence of alcohols and, in some cases, urea. In German ApplicationNo.31 22 013, N,N'-diarylureas are cited as the carboxylic acidderivatives, and in German Application No. 30 35 354, dialkylcarbonatesare cited as the carboxylic acid derivatives.

In addition, Methoden der organischen Chemie, Houben-Weyl, vol. 8,mentions the alcoholysis of unsubstituted allophanates of formula H₂N-CO-NH-CO-OR to form N-unsubstituted carbamates (p. 206). No industrialteachings are given on the preparation of N-substituted urethanes.

German Application No. 31 08 067 describes a process for the preparationof N,o-disubstituted urethanes by reacting primary amines and alcoholswith allophanates or mixtures of allophanates, urea, and/or carbamates,said mixtures possessing allophanates, at temperature of from 130° to350° C. The presence of amines is absolutely necessary for the reactionto take place. This is also demonstrated by the examples.

DESCRIPTION OF THE PREFERRED EMBODIMENT

It was now unexpectedly discovered that N,o-substituted mono- and/orpolyurethanes can be prepared in a simple manner and with good yieldwhen N-substituted allophanates and/or polyallophanates are alcoholized.

Hence, the subject of the invention is a process for the preparation ofN,o-substituted mono- and/or polyurethanes of formula

    R.sup.1 [-NHCOOR.sup.2 ].sub.n,

in which

R¹ is an aliphatic, cycloaliphatic, aromatic, araliphatic, orheterocyclic radical, which may be substituted,

R² is an aliphatic, cycloaliphatic, or araliphatic radical which may besubstituted with alkoxy or polyoxyalkylene groups, which may be the sameor different if n is greater than 1, and

n is a whole number from 1 to 5,

wherein N-substituted allophanates acid and/or polyallophanate isreacted with alcohols R² OH in the absence or, preferably, in thepresence of catalysts at temperatures of at least 160° C.

The process of the invention advantageously permits the N-substitutedallophanates and/or polyallophanates obtained as by-products in thethermal cleavage of urethanes to isocyanates to be converted intourethanes, and thus made accessible for the preparation of isocyanate.

Allophanates and/or polyallophanates suitable for use as startingcomponents, which may be exemplified for monovalent R₁ radicals by theformula

    R.sup.1 --NH[--CONR.sup.1 --].sub.x --COOR.sup.3,

in which R¹ has the meaning described above, R³ is an aliphatic,cycloaliphatic, aromatic, araliphatic, or heterocyclic radical, whichmay be substituted, and which preferably corresponds to the radical R²,and x is a whole number of at least 1, preferably from 1 to 4, can beprepared according to known methods. Typical methods are the acylizationof alcohols with substituted urea chloride or substituted allophanicacid chloride, or the direct introduction of the carboxylic ester groupto the substituted urea with a carboxylic acid dialkyl ester or alkylchloroformate. The substituted allophanates and/or polyallophanates arepreferably prepared through the reaction of urethanes or alcohols withone or more moles of isocyanate or they are accumulated as by-products,corresponding to this reaction, especially in the thermal cleavage ofurethanes to form isocyanates.

Suitable R² OH alcohols for the process of the invention are linear orbranched alkanols having from 1 to 18, preferably 1 to 10, and morepreferably 3 to 6 carbon atoms, linear or branched alkanols substitutedwith alkoxy groups having from 1 to 4 carbon atoms or polyoxyalkylenegroups, said alkanols containing from 2 to 24 carbon atoms, preferablyfrom 4 to 8 carbon atoms, cycloaliphatic alcohols having from 4 to 12carbon atoms, preferably from 6 to 8 carbon atoms, and/or araliphaticalcohols having from 7 to 15 carbon atoms, preferably from 7 to 10carbon atoms. Specific examples of such alcohols are: methanol, ethanol,propanol, isopropanol, butanol, isobutanol, pentanol, isopentanol,hexanol, isohexanol, heptanol, isoheptanol, octanol, isooctanol,nonanol, isononanol, decanol, isodecanol, dodecanol, 2-ethylhexanol,2-ethylbutanol, hexadecanol, octadecanol, 2-methoxyethanol,2-ethoxyethanol, 2-propoxyethanol, 2-butoxyethanol,2-(2-methoxyethoxy)ethanol, 2-(2-butoxyethoxy)ethanol, cyclopentanol,cyclohexanol, methylcyclohexanols, cyclohexamethanol,3,3,5-trimethylcyclohexanol, 4-tert.-butylcyclohexanol,2-hydroxydecalin, Borneol, Isoborneol, 2-hydroxyethoxybenzene, benzylalcohol, 2-phenylethanol, 2-(methoxyphenoxy)ethanols, 1-phenylethanol,3-phenyl-1-propanol, 4-methoxybenzyl alcohol.

Especially desirable and, therefore, preferred alcohols are: methanol,ethanol, n-propanol, isopropanol, n-butanol, isobutanol, n-pentanol,hexanol, heptanol, octanol, nonanol, decanol, ethylhexanol,cyclopentanol, benzyl alcohol, cyclohexanol, and 2-phenylethanol. Thesealcohols can be used separately or in the form of mixtures.

Since the alcohols are preferably used in a molar excess in the processof the invention, it is generally not necessary to add solvents.However, when special alcohols are used, it may be desirable to mix suchalcohols with solvents or solvent mixtures which are inert at thereaction conditions, nonpolar, or preferably polar, and which haveboiling points from 50° to 350° C. Typical examples of such solventsare: n-nonane, n-decane, n-dodecane, n-butylcyclohexane,n-hexylcyclohexane, decahydronaphthalene, isopropylbenzene,1,3-diethylbenzene, n-butylbenzene, chlorobenzene, 4-chlorotoluene,1,2-dichlorobenzene, 2,4-dichlorotoluene, 1,2,4-trichlorobenzene,2-chloro-4-isopropyl-1-methylbenzene, anisol, cyclohexylethyl ether,diethylene glycol dimethyl ether, benzyl methyl ether, 4-methoxytoluene,parachloroanisol, di-n-hexyl ether, N,N-dimethylformamide,N,N-diethylformamide, N-methylformamide, dimethylacetamide,N-methylpyrrolidone, caprolactam, tetraline, sulfolane,hexamethylphosphoric acid triamide, dimethyl sulfoxide, ethylene glycolmonomethyl ether acetate, Di-n-propyl carbonate, cyclohexyl acetate,diisobutyl carbonate, 2-ethylpyridine, N,N-dimethyl-2-methylaniline,N,N-dimethylaniline, N-methyl-N-ethylaniline,N,N-dimethyl-2-chloroaniline, N,N-diethylaniline, quinoline,nitrobenzene, 2-nitrotoluene, 2,4-dimethyl-1-nitrobenzene, acetonitrile,N-capronitrile, benzonitrile, tolunitrile, and phenylacetonitrile.

The alcoholysis of the allophanates and/or polyallophanates can beperformed in the absence of catalysts. In order to increase the rate ofreaction, and, hence, volume/time yield, it has been found to beadvantageous to perform the reaction in the presence of one or morecatalysts. Suitable catalysts are inorganic and organic compoundscontaining one or more, preferably one, cation of the metals in groupsIA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA, VB, VIB, VIIB and VIIIB ofthe periodic system, defined in accordance with the Handbook ofChemistry and Physics, 14th Edition, (Cleveland, Ohio: Chemical RubberPublishing Co., 2310 Superior Ave., N.E.), for example, halogenides suchas chlorides and bromides, sulfates, phosphates, nitrates, borates,alcoholates, phenolates, sulfates, oxides, oxide hydrates, hydroxides,carboxylates, chelates, carbonates, and thio- or dithiocarbamates.Typical cations are those of the following metals: lithium, sodium,potassium, magnesium, calcium, aluminum, gallium, tin, lead, bismuth,antimony, copper, silver, gold, zinc, mercury, cerium, titanium,vanadium, chromium, molybdenum, manganese, iron, cobalt, and nickel.Preferably, the cations of lithium, calcium, aluminum, tin, bismuth,antimony, copper, zinc, titanium, vanadium, chromium, molybdenum,manganese, iron, and cobalt are used. The catalysts can also be usedwithout significant disadvantages in the form of their hydrates orammoniates.

The following compounds are typical examples of such catalysts: lithiummethanolate, lithium ethanolate, lithium propanolate, lithiumbutanolate, sodium methanolate, potassium tert-butanolate, magnesiummethanolate, calcium methanolate, tin(II)chloride, tin(IV)chloride, leadacetate, lead phosphate, antimony(III)chloride, antimony(V)chloride,aluminum isobutylate, aluminum trichloride, bismuth(III)chloride,copper(II)acetate, copper(II)sulfate, copper(II)nitrate,bis(triphenylphospheneoxide)-copper-(II)-chloride, copper molybdate,silver acetate, gold acetate, zinc oxide, zinc chloride, zinc acetate,zinc acetonylacetate, zinc octoate, zinc oxalate, zinc hexylate, zincbenzoate, zinc undecylenate, cerium(IV)oxide, uranyl acetate, titaniumtetrabutanolate, titanium tetrachloride, titanium tetraphenolate,titanium naphthenate, vanadium(III)chloride, vanadium acetonylacetate,chromium(III)chloride, molybdenum(IV)oxide, molybdenum acetylacetonate,tungsten(VI)oxide, manganese(II)chloride, manganese(II)acetate,manganese(III)-acetate, iron(II)acetate, iron(III)acetate, ironphosphate, iron oxalate, iron(III)chloride, iron(III)bromide, cobaltacetate, cobalt chloride, cobalt sulfate, cobalt naphthenate, nickelchloride, nickel acetate, and nickel naphthenate as well as mixtures ofsuch catalysts.

The catalysts are appropriately utilized in amounts from 0.0001 to 10weight percent, preferably from 0.0001 to 3 weight percent, and morepreferably, from 0.0005 to 1 weight percent, based on the weight of theallophanate and/or polyallophanate. In a special embodiment, the metalcations can also be present in the reaction mixture in a heterogeneousphase, for example, bound to ion exchangers.

The preparation of N,o-substituted mono- and/or polyurethanes inaccordance with the process of the invention involves reacting theallophanates and/or polyallophanates with alcohols, preferably thosecorresponding to ester alcohols, in amounts per [--CO--NR¹ --] group offrom 1 to 5 moles, preferably from 3 to 15 moles, and more preferablyfrom 3 to 5 moles.

If the ester alcohols R³ OH used as the basis of the allophanates and/orpolyallophanates and the alcohols R² OH, which are utilized, areidentical, a transesterification occurs to a greater or lesser degree inaddition to the alcoholysis. This results in polyurethanes and/orpolyurethane mixtures with different ester groups. By suitably selectingthe starting components, in particular the R² OH alcohols, and theamounts of the starting components, however, nearly completeesterification can be achieved at the same time as the alcoholysis. Thisversion , of the process, alcoholysis with simultaneoustransesterification, is particularly important when the mono- and/orpolyurethanes are thermally cleaved into isocyanates and alcohols andthe resulting cleavage products would have nearly the same boilingpoints without prior transesterification.

By reducing the amount of excess alcohol, the degree oftransesterification can be reduced. However, it has proven to bedesirable to perform the alcoholysis in the presence of solvents at[--CO--NR¹ --] group-to-alcohol ratios of 1:1 to approximately 1:2.

The alcoholysis is performed at temperatures of at least 160° C.,preferably from 165° to 250° C., and more preferably from 180° C. to230° C. and at pressures of from 0.1 to 120 bar, preferably from 0.5 to60 bar, and more preferably from 1 to 40 bar. At a given temperature,the reaction is then preferably performed under the intrinsic pressureof the reaction mixture.

For the temperature range cited, reaction times of from 0.5 to 100 hoursresult, preferably from 1 to 50 hours, and more preferably from 2 to 25hours.

The mono- and/or polyurethanes are appropriately prepared in accordancewith the process as follows. The allophanates and/or polyallophanatesand R² OH alcohols are mixed in the cited quantitative ratios and, insome cases, in the presence of a catalyst and solvent, in a reactionvessel and heated, in some cases, while stirring. Then the mono- and/orpolyurethanes are isolated from the resulting reaction mixture, in somecases after removal of the catalyst and filtering off of solids, forexample by distilling off the excess alcohol, partially distilling offthe excess alcohol, and removal through crystallization, byprecipitating with other solvents or by recrystallization out of othersolvents. If desired, the removed alcohol can be recycled.

In accordance with the process of the invention, as already described,mono- and/or polyurethanes can be prepared which have the formula

    R.sup.1 [--NHCOOR.sup.2 ].sub.n,

where:

n is a whole number from 1 to 5, preferably 2 to 3, indicating thefunctionality,

R¹, depending on the functionality of n, is a 1- to 5-valent, preferably2- to 3-valent, substituted or, preferably unsubstituted, aliphatichydrocarbon radical having from 1 to 18, preferably 3 to 10, carbonatoms; substituted or, preferably unsubstituted, cycloaliphatic radicalhaving from 3 to 18, preferably 6 to 13, carbon atoms; substituted or,preferably unsubstituted, aromatic hydrocarbon radical having from 6 to15, preferably from 6 to 10, carbon atoms; a substituted or, preferablyunsubstituted, aralaliphatic hydrocarbon radical having from 7 to 34carbon atoms, preferably from 8 to 20 carbon atoms, or a substituted or,preferably unsubstituted, 5- to 6-member heterocyclic radical, which canalso be connected to a benzene ring, and

R² is a linear or branched alkyl radical having from 1 to 18, preferably1 to 10, and more preferably 3 to 6, carbon atoms; a linear or branchedalkyl radical having from 2 to 24, preferably 4 to 8, carbon atoms,substituted with alkoxy groups having from 1 to 4 carbon atoms orpolyoxyalkylene groups, for example, polyoxyethylene and/orpolyoxypropylene groups, or a substituted or unsubstituted cycloalkylradical having from 4 to 12 carbon atoms, preferably from 6 to 8, and/ora substituted or unsubstituted arylaliphatic hydrocarbon radical havingfrom 7 to 15 carbon atoms, preferably 7 to 10.

Typical substituents for the 1- to 5-valent aliphatic and cycloaliphaticradical R¹ are, for example: alkoxy groups having from 1 to 6,preferably 1 to 4, carbon atoms, aryoxy groups having from 6 to 10carbon atoms, preferably 6 to 8, acyl radicals having from 2 to 6 carbonatoms, alkylmercapto groups having from 1 to 6 carbon atoms,arylmercapto groups having from 6 to 10 carbon atoms, alkylcarbonylgroups having from 1 to 10 carbon atoms, dialkylamino groups having from1 to 10 carbon atoms, acylamino groups having from 1 to 8 carbon atoms,arylcarbonyl groups having from 7 to 9 carbon atoms, nitro groups, cyanogroups, and halogen atoms.

The following 1- to 5-valent araliphatic and aromatic radicals R¹ can bementioned as examples in addition to the substituents for the R¹aliphatic and cycloaliphatic radicals cited above: linear or branchedalkyl radicals having from 1 to 12, preferably from 1 to 4, carbonatoms, alkylsulfonates having from 1 to 10, preferably 1 to 4, carbonatoms in the linear or branched alkyl radical, and sulfonamide groups.

Preferred R¹ radicals are those which can be derived, for example, fromthe following primary amines: aliphatic and cycloaliphatic monoaminessuch as methylamine, ethylamine, propylamine, isopropylamine,n-butylamine, secbutylamine, tert-butylamine, isobutylamine, 2- and3-methylbutylamine, neopentylamine, n-pentylamine, 2-methylpentylamine,sec-isoamylamine, n-hexylamine, 2-methylhexylamine, 2-ethylhexylamine,n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, n-dodecylamine,2-phenylpropylamine, benzylamine, cyclopentylamine, cyclohexylamine,tertbutylcyclohexylamine, aliphatic diamines such as ethylenediamine,1,3- and 1,2-propylenediamine, 2,2-dimethyl-1,3-propylenediamine,2,2-dimethyl-1,3-propylenediamine, 1,4-butylenediamine,1,5-pentamethylenediamine, 1,6-hexamethylenediamine,2,2,4-trimethyl-1,6-hexamethylenediamine, 1,8-octamethylenediamine,1,10-decylenediamine, 1,12-dodecylenediamine and 3,3'-diaminodipropylether, cycloaliphatic diamines such as 1,2-, 1,3-, and1,4-cyclohexanediamine, 2,4- and 2,6-hexahydrotoluenediamine, as well ascorresponding isomer mixtures, 1,4-hexahydroxylylenediamine, 4,4'-,2,4'-, and 2,2'-diaminodicyclohexylmethane as well as correspondingisomer mixtures, 2,2-di(4-aminocyclohexyl)propane,3-aminomethyl-3,5,5-trimethylcyclohexylamine, and dicyclopentadienylcompounds of formula ##STR1## diamines containing heterocyclic radicalsin bound form, such as, in some cases, substitutedN,N'-bis(aminoalkyl)piperazines, for example,N,N'-bis(2,2-dimethyl-3-aminopropyl)piperazine, andN,N'-bis(aminopropyl)piperazine, aromatic monoamines such as aniline,substituted anilines, such as anilines substituted in the 2-, 3-, and/or4-position by a nitro, methyl, ethyl, n-propyl, isopropyl, n-butyl,isobutyl, sec-butyl, tert-butyl group or by a chlorine atom, as well assimilarly substituted ortho-, meta-, and/or para-hydroxy-, methoxy-,ethoxy-, propoxy-, isopropoxy-, N-butoxy-, isobutoxy-, sec-butoxy-, andtertbutoxyaniline; alkylbenzoates which are substituted by an aminogroup in the m- and/or p-position and contain from 1 to 12 carbon atomsin the alkyl radical, by N-alkoxycarbonylaminobenzenes and tolueneswhich are substituted by an amino group in the m- and/or p-position andwhich contain from 1 to 4 carbon atoms in the alkyl radical; α- andβ-naphthylamine; aromatic diamines such as 1,3- and 1,4-diaminobenzene;1,4-diaminobenzene, 1,5- and 1,8-diaminonaphthalene,4,4'-diaminodiphenyl, 2,2'-, 2,4'-, and 4,4'-diaminodiphenylmethanesubstituted in the 2- and/or 4-position by a methyl, ethyl, n-propyl,isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, methoxy, ethoxy,n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxygroup or a halogen atom, preferably a fluorine and/or a chlorine atom,and by the corresponding isomer mixtures as well as aromatic polyaminessuch as 1,3,5-triaminobenzene, 2,4,6-triaminotoluene,1,3,5-triaminonaphthalene, and polyphenyl polymethylene polyamines aswell as mixtures of diaminodiphenylmethanes and polyphenyl polymethylenepolyamines.

Mono- and/or polyurethanes prepared in accordance with the process ofthe invention are valuable final products and intermediates. They areused as final products, for example, for pest control. As intermediates,they are used, for example, as components in condensation polymerizationsystems and polymer systems. In particular, though, they are transformedto the corresponding isocyanates by cleaving off alcohols, whereby di-and polyisocyanates are utilized to prepare polyurethane plastics.

The parts cited in the examples represent parts by weight. The elementalcompositions and structures were determined by means of massspectroscopy as well as IR and NMR spectra.

EXAMPLE 1

A mixture of 8.6 g N,N'-diphenylallophanic acid butyl ester and 15.9 gN-phenylbutylurethane was stirred with 58.1 g n-butanol for five hoursat 210° C. After the reaction mixture had cooled, the excess n-butanolwas distilled off, and 25.5 g N-phenylbutylurethane (90.2 percent oftheoretical) was obtained after purification in a thin-film evaporator.The conversion of allophanate was quantitative.

A mixture of the starting components N,N'-diphenylallophanic acid butylester and N-phenylbutylurethane was obtained by stirring n-butanol withthe distillation bottoms produced in the purification distillation ofphenyl isocyanate, which, in turn, was produced by the thermal cleavageof N-phenylbutylurethane.

EXAMPLE 2

A mixture of 26 g of an allophanate obtained from2-butoxycarbonylaminotoluene-4-isocyanate and 2,4-toluenedibutylurethane and 14 g 2,4-toluene dibutylurethane, obtained bystirring the distillation bottoms off the purification distillation of2,4-toluene diisocyanate obtained through the thermal cleavage of2,4-toluene dibutylurethane, was stirred for five hours at 210° C. with51.8 g n-butanol. After cooling the reaction mixture, the excessn-butanol was distilled off, and a residue was obtained which contained42.8 g, 2,4-toluene dibutylurethane, based on HPLC analysis, (98.0percent of theoretical). Allophanate was not detected any longer.

EXAMPLE 3

In the purification distillation of a 1,6-hexamethylene diisocyanateobtained through the thermal cleavage of 1,6-hexamethylenedibutylurethane, 135 g of a mixture comprising 85 weight percent6-(butoxycarbonylamino)hexylisocyanate and 15 weight percent1,6-hexamethylene diisocyanate were heated at temperatures of 155° C to165° C in the base of a distillation flask for an average of two hours.Here the result was a mixture comprising approximately 18 weight percent6-(butoxycarbonylamino)hexylisocyanate and various polyisocyanatohexamethylene allophanic butyl esters.

An amount of 310 g n-butanol and 1 g iron(III)acetate were added to thismixture and the resulting mixture was then heated in a pressurizedapparatus for five hours at 220° C. After cooling, the reaction mixturewas analyzed using gas chromatography. An amount of 183 g1,6-hexamethylene dibutylurethane was obtained. This meant that thepolyisocyanato hexamethylene allophanic acid butyl esters were convertedto diurethane at a nearly quantitative rate.

EXAMPLE 4

A procedure similar to that in Example 3 was followed, however, 78 g ofa mixture comprising approximately 16 weight percent of6-(butoxycarbonylamino)hexylisocyanate, 450 g of n-octanol instead ofn-butanol, and 0.5 g iron(III)acetate were used.

The reaction mixture was boiled for three hours, during which time then-butanol cleaved off was removed by distillation, and after thereaction mixture had cooled, the excess n-octanol was distilled off atreduced pressure. The result was 153 g of a residue which thin-layeranalysis revealed to consist of nearly quantitative amounts of1,6-hexamethylene dioctylurethane.

The embodiments of the invention in which an exclusive privilege orproperty is claimed are defined as follows:

What is claimed is:
 1. A process for the preparation of N,o-substitutedmono- and/or polyurethanes of the formula

    R.sup.1 [-NHCOOR.sup.2 ].sub.n,

in which n is a whole number for 1 to 5, R¹ is selected from the groupconsisting of an aliphatic, hydrocarbon radical having from 1 to 18carbon atoms, a cycloaliphatic hydrocarbon radical having from 3 to 18carbon atoms, an araliphatic hydrocarbon radical having from 7 to 34carbon atoms, and a 5 to 6 member heterocyclic radical, R² is selectedfrom the group consisting of an alkyl radical having from 1 to 18 carbonatoms, a cycloalkyl radical having from 4 to 12 carbon atoms, an aralkylradical having from 7 to 5 carbon atoms, and an alkyl radical havingfrom 2 to 24 carbon atoms substituted with alkoxy groups orpolyoxyalkylene groups which may be the same or different if n isgreater than 1, wherein N-substituted allophanic acid and/orpolyallophanate is reacted with alcohols in the presence or absence ofcatalysts at temperatures of at least 160° C.
 2. The process of claim 1wherein the reaction is performed at temperatures from 165° to 250° C.3. The process of claim 1 wherein the reaction is performed in thepresence of catalysts.
 4. The process of claim 1 wherein from 0.0001 to10 percent by weight of at least one cation of metals from groups IA,IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA, VB, VIB, VIIB, VIIIB in theperiodic system based on the weight of the allophanic acid and/orpolyallophanate is used as a catalyst.
 5. The process of claim 1 whereinfrom 1 to 50 moles alcohol is used per --[CONR¹ ]-- group in theallophanic acid and/or polyallophanate.
 6. The process of claim 1wherein the corresponding alcohol is used in the allophanic acid and/orpolyallophanate.
 7. The process of claim 1 wherein the alcohol is mixedwith a solvent said solvent being inert at the reaction conditions. 8.The process of claim 1 wherein the alcohol is selected from the groupconsisting of linear or branched alkanols having from 1 to 18 carbonatoms, alkanols having from 2 to 24 carbon atoms substituted with alkoxygroups having from 1 to 4 carbon atoms or polyoxyalkylene groups,cycloaliphatic alcohols having from 4 to 12 carbon atoms, and/oraraliphatic alcohols having from 7 to 15 carbon atoms.
 9. The process ofclaim 1 wherein methanol, ethanol, n-propanol, iso-propanol, n-butanol,iso-butanol, n-pentanol, hexanol, ethylhexanol, heptanol, octanol,nonanol, decanol, cyclopentanol, benzyl alcohol, cyclohexanol and/or2-phenylethanol ar®used as the alcohols.